Intra-body probes, such as catheters, are used in various medical applications. Such probes include, for example, balloon angioplasty catheters, catheters for laser-, electrical- or cryo-ablation, probes used for nearly incision-less surgery or diagnosis, and endoscopes. Such probes are sometimes equipped with position sensors that enable an external system to measure their location within a patient's body.
For example, U.S. Pat. No. 6,690,963, whose disclosure is incorporated herein by reference, describes a catheter comprising a locating sensor at the distal end. The locating sensor comprises two or three antennas, for example coils, which are irradiated by two or three radiators, for example coils, located outside the body surface of the patient. The three radiators are driven by radiator drivers. The signals received by the receiving antennas are amplified and processed, together with a representation of the signals used to drive the radiators, to provide a display, or other indication, of the position and orientation of the distal end of the catheter.
U.S. Pat. No. 6,253,770, whose disclosure is incorporated herein by reference, describes a catheter having a lumen, which is obstructed by a portion of the catheter. The catheter includes a position detector at the tip of the catheter.